Discovery of pairing of electrons in artificial atoms
Researchers at the Department of Physics at the University of Hamburg have observed a previously undetectable quantum state that was theoretically predicted by Japanese theorists more than 50 years ago. By making artificial atom Researchers have successfully paired the electrons of so-called quantum dots on the surface of a superconductor, thereby inducing the smallest possible superconductor.The work will be published in the latest issue of the magazine Nature.
Electron behavior and superconductivity
Electrons usually repel each other due to their negative charge. This repulsive phenomenon plays an important role in influencing many material properties, one of which is electrical resistance. However, the situation changes dramatically when electrons are “glued” into pairs to become bosons. Unlike lone electrons that repel each other, boson electron pairs can coexist in the same space and perform the same motion.
One of the most interesting properties of materials containing these electron pairs is their superconductivity, the ability to pass current without resistance. Over the years, superconductivity has been used in many technical applications such as magnetic resonance imaging and sensitive magnetic field detectors. As electronics continue to shrink, there is growing interest in understanding how superconductivity can be achieved in smaller sizes. nano scale Structure.
Electron pairing in artificial atoms
Researchers at the University of Hamburg’s Department of Physics and the Cluster of Excellence “CUI: Advanced Imaging of Matter” have realized pairs of electrons in artificial atoms called quantum dots, the smallest building blocks of nanostructured electronic devices. To this end, experimenters led by Dr. Jens Wiebe PD at the Institute for Nanostructured Condensed Matter Physics confined electrons, atom by atom, in small cages made of silver.
By binding locked electrons to elemental superconductors, the electrons inherited the pairing tendency from superconductors. Working with a team of theoretical physicists from the cluster led by Dr. Torre Posquet, the researchers predicted spectroscopic peaks at very low energies, a signature of the experiments Kazunari Machida and Dr. Kazunari Machida in the early 70s of the last century. associated with the quantum state Mr. Fumiaki Shibata.
This state has so far eluded direct detection by experimental methods, but recent work by a Dutch and Danish team has shown that it suppresses unwanted noise in transmon qubits, a key building block of modern quantum computers. It has been shown to be beneficial for
Kazunari Machida wrote in a private email to Dr. Lucas Schneider, lead author of this publication: “Thank you for “discovering” my old paper from half a century ago. I have long believed that non-magnetic impurities in transition metals produce in-gap states, but their positions are so close to the superconducting gap edge that their existence has been impossible to prove. But your ingenious methods finally experimentally confirmed it to be true. ”
Reference: “Proximity Superconductivity in Atom-by-Atom Quantum Dots,” Lucas Schneider, Khai That Ton, Ioannis Ioannidis, Jannis Neuhaus-Steinmetz, Thore Posske, Roland Wiesendanger, Jens Wiebe, 16 Aug. 2023, Available here. Nature.
DOI: 10.1038/s41586-023-06312-0